The invention relates to a novel capsule for receiving an active substance to be administered by inhalation, which is preferably intended for use in a powder inhaler operating on the Bernoulli principle.
A number of powder inhalers operating by various principles are known in the literature. What they all have in common is that the active substance to be delivered is stored in a generally cylindrical capsule and this capsule is inserted in a capsule chamber of the inhaler.
A suitable powder inhaler consists essentially of a preferably cylindrical capsule chamber provided with means for laterally opening the capsule, an air inlet opening in the capsule chamber and an air outlet opening and a mouthpiece provided downstream of the air outlet opening. The capsule chamber is usually cylindrical in shape, being somewhat longer and wider than the capsule so that the capsule is able to vibrate both axially and radially therein, but remains aligned substantially parallel to the chamber axis. The terms axial and radial are equivalent to vertical (axial) and horizontal (radial) with respect to the orientation of the inhaler in which the capsule chamber is aligned below the mouthpiece. Axial also denotes an orientation parallel to the longitudinal axis of the inhaler (vertical axis), while radial is the direction perpendicular thereto. The capsule chamber has an air inlet in the region of one of its two ends and an air outlet opening in the region of its other end. The air outlet which can carry a powder aerosol leads to a mouthpiece. In order to deliver the active capsule contents, first of all the capsule may be opened, normally at two places on its longitudinal casing. As a rule the openings are located close to the two longitudinal ends of the capsule. If an air stream is now generated from the air inlet towards the air outlet in the capsule chamber, it runs along the longitudinal axis of the capsule and has two effects: on the one hand the capsule is moved mainly along its longitudinal axis by the air stream. It can also vibrate to a small degree. On the other hand, the air flowing along the two capsule openings produces a lower pressure in front of the capsule openings than inside the capsule, so that the powder contained in the capsule is picked up by the air stream and thereby nebulised.
DE 3345722 discloses an inhaler of this kind consisting of two housing elements which are axially moveable towards each other, with a single capsule chamber.
WO 91/02558 discloses another inhaler as described hereinbefore wherein instead of a single capsule chamber there are a plurality of capsule chambers arranged in a similar manner to a revolver magazine. The open ends of this magazine are delimited by walls, the air inlet or air outlet being located only at one point in these walls. This magazine is mounted to be rotatable so that a capsule chamber is only connected to the air inlet, the air outlet and the cutting elements required to open the capsule in a certain position.
EP 0911047 discloses an inhaler with a) a cup-shaped lower part open upwardly, b) a plate which covers the opening in the lower part and perpendicular to which is formed a capsule chamber, whilst on the capsule chamber is provided a button which is moveable against a spring which has two sharp spikes for opening the capsule, c) an upper part with a mouth tube which is connected to the capsule chamber, and capable of conveying a powder aerosol, and d) a lid. The elements a), b), c) and d) are joined together by a common hinge element so that they can be flipped relative to each other. In addition, this patent application describes a capsule holder wherein the capsule holder may be constructed as a hole in the plate b) and has ribs at the edge. The capsule is jammed into this capsule holder to hold it in readiness.
The capsules normally used for inhalers of this kind consist of hard gelatine but may also consist of a plastic material. In connection with this reference is made to EP 1100474.
The capsules known from the prior art consist of two cup-like components which fit telescopically one inside the other, the capsule cap and the capsule body. The outer shape of a composite capsule of this kind is that of a closed cylinder with hemispherical ends. The cylinder has a longitudinal axis and a transverse axis. The longitudinal axis is the axis which runs parallel to the generatrix of the cylinder casing. The longitudinal axis is longer than the transverse axis with the result that the longitudinal section of the capsule has an oval geometry and the cross section has a circular geometry. Many capsules have an encircling groove at the join between the capsule cap and capsule body, produced by the fact that the capsule cap always has a somewhat larger external diameter than the capsule body. In connection with this, reference is made to EP 1100474 or PCT/EP0207481. If for example cross sectional drawings of the two parts of the capsule are superimposed, it will be seen that the two outer contours are not congruent.